List of Grand Prix motorcycle racing World Champions by year
List

Year
500cc
350cc
250cc
125cc
Sidecar
1949
United Kingdom Leslie Graham (AJS)
United Kingdom Freddie Frith (Velocette)
Italy Bruno Ruffo (Moto Guzzi)
Italy Nello Pagani (Mondial)
United Kingdom Eric Oliver United Kingdom Denis Jenkinson (Norton)
1950
Italy Umberto Masetti (Gilera)
United Kingdom Bob Foster (Velocette)
Italy Dario Ambrosini (Benelli)
Italy Bruno Ruffo (Mondial)
United Kingdom Eric Oliver Italy Lorenzo Dobelli (Norton)
1951
United Kingdom Geoff Duke (Norton)
United Kingdom Geoff Duke (Norton)
Italy Bruno Ruffo (Moto Guzzi)
Italy Carlo Ubbiali (Mondial)
United Kingdom Eric Oliver Italy Lorenzo Dobelli (Norton)
1952
Italy Umberto Masetti (Gilera)
United Kingdom Geoff Duke (Norton)
Italy Enrico Lorenzetti (Moto Guzzi)
United Kingdom Cecil Sandford (MV Agusta)
United Kingdom Cyril Smith United Kingdom Bob Clements United Kingdom Les Nutt (Norton)
1953
United Kingdom Geoff Duke (Gilera)
United Kingdom Fergus Anderson (Moto Guzzi)
West Germany Werner Haas (NSU)
West Germany Werner Haas (NSU)
United Kingdom Eric Oliver United Kingdom Stanley Dibben (Norton)
1954
United Kingdom Geoff Duke (Gilera)
United Kingdom Fergus Anderson (Moto Guzzi)
West Germany Werner Haas (NSU)
Austria Rupert Hollaus (NSU)
West Germany Wilhelm Noll West Germany Fritz Cron (BMW)
1955
United Kingdom Geoff Duke (Gilera)
United Kingdom Bill Lomas (Moto Guzzi)
West Germany Hermann Paul Müller (NSU)
Italy Carlo Ubbiali (MV Agusta)
West Germany Willi Faust West Germany Karl Remmert (BMW)
1956
United Kingdom John Surtees (MV Agusta)
United Kingdom Bill Lomas (Moto Guzzi)
Italy Carlo Ubbiali (MV Agusta)
Italy Carlo Ubbiali (MV Agusta)
West Germany Wilhelm Noll West Germany Fritz Cron (BMW)
1957
Italy Libero Liberati (Gilera)
Australia Keith Campbell (Moto Guzzi)
United Kingdom Cecil Sandford (Mondial)
Italy Tarquinio Provini (Mondial)
West Germany Fritz Hillebrand West Germany Manfred Grunwahl (BMW)
1958
United Kingdom John Surtees (MV Agusta)
United Kingdom John Surtees (MV Agusta)
Italy Tarquinio Provini (MV Agusta)
Italy Carlo Ubbiali (MV Agusta)
West Germany Walter Schneider West Germany Hans Strauß (BMW)
1959
United Kingdom John Surtees (MV Agusta)
United Kingdom John Surtees (MV Agusta)
Italy Carlo Ubbiali (MV Agusta)
Italy Carlo Ubbiali (MV Agusta)
West Germany Walter Schneider West Germany Hans Strauß (BMW)
1960
United Kingdom John Surtees (MV Agusta)
United Kingdom John Surtees (MV Agusta)
Italy Carlo Ubbiali (MV Agusta)
Italy Carlo Ubbiali (MV Agusta)
West Germany Helmut Fath West Germany Alfred Wohlgemuth (BMW)
1961
Federation of Rhodesia and Nyasaland Gary Hocking (MV Agusta)
Federation of Rhodesia and Nyasaland Gary Hocking (MV Agusta)
United Kingdom Mike Hailwood (Honda)
Australia Tom Phillis (Honda)
West Germany Max Deubel West Germany Emil Hörner (BMW)

Question: How many Grand Prix World Championships has Bruno Ruffo won?
Answer: Bruno Ruffo won three Grand Prix World Championships.